1. Field of the Invention
The present invention relates to a method of manufacturing an electronic component in which an electronic component element such as a surface acoustic wave element or a semiconductor element is bonded via a bump to electrically and mechanically connect the electronic component element to a base member.
2. Description of the Related Art
Electronic component elements which are bump-bonded so as to be mounted on base members and so as to hermetically seal the electronic components in packages by bonding the base members to cap members are known. In such electronic components, electronic component elements are opposed to the base members, and electrode pads of the electronic component elements are bonded to corresponding electrode lands of the base members via bumps made of Au or other suitable material so as to supportively fix and electrically connect the electronic component elements to the base members. After that, cap members are bonded to the base members by seam welding or by using a brazing material such as solder to produce electronic components.
The above-described bump bonding is performed by positioning the electronic component elements opposite to the base members, and, for example, heat and pressure are applied while applying an ultrasonic wave. Usually, the time of the bump bonding (application of an ultrasonic wave, heat, and pressure) is approximately one second or less. The conditions for bonding, such as an ultrasonic wave output to be applied, pressure to be applied (load), and a temperature are set such that a higher degree of bonding strength (sharing strength) can be obtained. For example, in Japanese Unexamined Patent publication No. 10-07078, an ultrasonic wave output is in a range of 0.04 to 0.42 W/bump, and an applied pressure is in a range of 150 to 350 gf/bump to perform bump bonding. With these conditions, a solid-phase diffusion area formed by the electrodes and the bumps is expanded, by which the strength of bump bonding can be increased.
However, in the above-described conventional method of manufacturing an electronic component, although the bonding strength can be increased by changing the bonding conditions during bump bonding, the time of bonding for achieving bump bonding is very short. Thus, there is a limitation to the expansion of the solid-phase diffusion area, and a sufficient bonding strength cannot be achieved. In other words, when bump bonding is performed, mutual diffusion of the bump material and the electrode material is generated to form the solid-phase diffusion area so as to achieve the bonding of the bumps and the electrodes. However, since the time of bonding is short when bump bonding is performed, it is impossible to obtain a sufficient solid-phase diffusion area only by bump bonding. In addition, there is a problem that a targeted bonding strength cannot be obtained due to variations in materials and dimensions of component members, and variations in bonding conditions occurring when bonding is performed.
In order to overcome the problems described above, preferred embodiments of the present invention provide a method of manufacturing a surface acoustic wave device, in which a solid-phase diffusion area define by a bump and an electrode bonded to the bump is expanded so as to increase the strength of bump bonding so as to prevent connection failures at the portion bonded by the bump and so that excellent reliability is achieved.
According to one preferred embodiment of the present invention, a method of manufacturing an electronic component includes the steps of bonding an electronic component element to a base member via a bump to electrically and mechanically connect the electronic component element to the base member and bonding a cap member to the base member in such a manner that the cap member covers the electronic component element. In this method, after the electronic component element is bonded to the base member via the bump, high temperature aging is performed.
With the above method for manufacturing an electronic component, the high temperature aging causes the solid-phase diffusion area defined by the bump, the electrode of the electronic component element, and the electrode of the base member, which are bonded to the bump, to be greatly expanded. In addition, the stable solid-phase diffusion area in which there are slight variations can be obtained, and the strength of bump bonding is greatly increased as a result.
The above-described high temperature aging may be performed either before or after the bonding of the base member and the cap member. Alternatively, when bump bonding is performed, high temperature aging may be performed following the bump bonding procedure.
Furthermore, high temperature aging may be performed at the same time, when the base member is bonded to the cap member. In this case, since it is necessary to simply add a time equivalent to the time used for the procedure of high temperature aging, the number of steps in the production process can be reduced.
Other features, characteristics, advantages and steps of preferred embodiments of the present invention will become more apparent from the detailed description below in conjunction with the attached drawings.
For the purpose of illustrating the invention, there is shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.